Cartridge fuse pull-out switch



24, 1965 I M. J. GEORGE 3,202,788

CARTRIDGE FUSE PULL-OUT SWITCH Filed March 22, 1962 2 Sheets-Sheet l INVENTOR. 51 B6 56 36 MeZz/z/z fwye Aug. 24, 1965 M. J. GEORGE CARTRIDGE FUSE PULL-OUT SWITCH 2 Sheets-Sheet 2 Filed March 22, 1962 United States Patent 3,292,738 (JAR'IRIDGE FUSE PULL-GUT SWITCH Meivin .I. George, Lexington, Ky assignorto Square 1) Company, Park Ridge, Ilh, a corporation of Michigan Filed Mar. 22, 1962;, Ser. No. 131,529 8 Claims. (@I. ass-133 This invention relates to fusible units including fuse blocks and pull-out type cartridge fuse holders receivable therein.

In certain former constructions, contact jaws provided in the fuse blocks were adapted to receive contact blade extensions of fuse clips on the fuse holder in such a manner that the pressure between a cartridge fuse and its fuse clips actually decreased upon insertion of the fuse holder in the fuse block. In certain other former constructions, pressure between a cartridge fuse and its fuse clips increased upon insertion of the fuse holder in the fuse block, but the increase in pressure was limited by engagement of one portion of each fuse clip with another portion thereof. In a fusible unit constructed in accordance with the present invention, the pressure between a fuse and its fuse clips increases upon insertion of the fuse holder in the fuse block, and the increase in pressure is not limited by engagement of one portion of each fuse clip with another portion thereof. Thus, a better electrical connection between a fuse and its fuse clips is made than formerly.

An object of the invention is to provide an improved fusible unit.

Another object is to provide a cartridge fuse pull-out unit wherein improved electrical connections are made between the fuses and the fusible unit.

. Yet another object is to provide a more compact fusible unit adapted to accommodate twice the number of fuses accommodated by former fusible units of the same size.

A further object is to provide a cartridge fuse pull-out unit wherein the fuse block is provided with an improved arrangement of live and dead pockets for the fuse holder to plug into in on and off positions, respectively.

Still another object is to provide an improved'duplex cartridge fuse pull-out unit having a fuse block adapted to be plugged into an electrical panelboard and having a pair of fuse holders each adapted to hold two cartridge fuses for respective connection to opposite sides of a load connected directly across two power lines.

Other objects will appear when the following specification is considered along with the accompanying drawings in which:

FIGURE 1 is a perspective view of a fusible unit constructed in accordance with the invention;

FIGURE 2 is a perspective view of one of the fuse holders of the fusible unit of FIGURE 1;

FIGURE 3 is an end view of the fusible unit of FIG- URE 1 looking at the line terminal end;

FIGURE 4 is a top view of the fuse block of the fusible unit of FIGURE 1;

FIGURE 5 is a perspective view of a contact jaw of a fuse block constructed in accordance with the invention;

FIGURE 6 is a sectional view taken substantially along line 6-6 of FIGURE 7 and including a fuse holder;

FIGURE 7 is a bottom view of the fuse block of the fusible unit of FIGURE 1;

FIGURE 8 is a sectional view taken substantially along line 8-8 of FIGURE 7 but omitting the line terminal clips and including a fuse holder; and

FIGURE 9 is a sectional view of a fuse holder as shown in FIGURE 8, but removed from the fuse block.

A fusible unit constructed in accordance with the invention may include a fuse block or base assembly 10 3,202,738: Patented Aug. 24-, 1965 and a pair of identical generally rectangular fuse holders or cover assemblies 12, 12 removably received in the fuse block It) as shown in FIGURES 1 and 3. The fuse block is molded of an insulating material and is provided with a pair of generally rectangular recesses 14, 14 (FIG- URES 4 and 7) opening to the front thereof and separated by a dividing wall 15. The walls defining each recess 14 are suitably grooved to slidably receive an insulating barrier 16 parallel to the wall 15 and bisecting the respective recess. The barriers 16 are formed of a material having high dielectric strength.

Each fuse holder 12 has two pairs of fuse clips 20, 20 secured to an inner side thereof in a rectangularly spaced arrangement as by screws 21 (FIGURE 9), and a handle 22 pivotally mounted on an outer or front side thereof. The fuse holders 12, 12 are adapted to be received in the recesses 14, 14, respectively, each fuse holder being provided on the inner side thereof with a central longitudinally extending groove 24 (FIGURE 9) adapted to receive one of the barriers 16 between adjacent pairs of the fuse clips 29, 20. Each fuse holder 12 is thus adapted to carry two cartridge fuses 25, 25 respectively in the pairs of fuse clips 26, 20. The outer jaw of each fuse clip 20 is provided with a contact blade extension 25.

For a purpose to be later described, on each fuse holder 12 the spacing of the fuse clips 26 2d of each pair longitudinally of the fuse holder is such that if the fuse holder is considered to be formed of four quarters sections extending consecutively lengthwise thereof, the clips 2t), 26 may be roughly considered to be secured to the first and third quarter sections.

A mounting clip 29 is secured by a screw 36 to the rear or inner side of the fuse block 10 adjacent one end, and adjacent the other end a pair of identical line terminal clips 31 and 32 are provided, the clips 31 and 32 being adapted to receive a pair of panelboa-rd branch bus bars or connectors (not shown) fed respectively by a pair of power supply lines.

A wall 34 defining the inner ends of the recesses 14 is provided with a plurality of rectangular holes 35 and 36 alternately spaced along the longitudinal edges of the recesses. The holes 35 extend completely through the wall 34 and each hole 35 receives one leg 38 of a. substantially L-shaped contact jaw 4i), one of which is shown in perspective in FIGURE 5, the assembled relationship being best shown in FIGURE 8. The holes 36 may extend completely through the Wall 34, except for a hole or pocket designated 36a, which for shielding purposes is closed at its inner end by a thickened portion of the wall 34'. For a purpose to be later described, the spacing of the holes 35, 3d, and 36a is such that if the wall 34 forming the inner ends of the recesses 14 is considered to be formed of four quarter sections extending consecutively lengthwise of the recesses, the holes 35 may be roughly considered to be in the first and third quarter sections, the holes 36 in the second and fourth quarter sections, and the hole 36a in the second quarter section. The first and third quarters of the Wall 34 are provided with thickened portions into which are threaded rom the rear of the wall 34 the shanks of a plurality of self-tappinng screws 42, which extend through legs 39 of the contact jaws 4-0 to secure them in position with the legs 33 thereof in the holes 35.

The screws 42 also secure various conductive straps or connectors in position. Thus, as shown in FIG- URES 7 and 8, in the third quarter of the Wall 34, a strap 43 and a connector 44 electrically connect the two inner contact jaws 4th to the line terminal clip 31, which is secured to the connector 44 by means such as a screw t5, and a generally U-shaped connector 46 and a connector 47 electrically connect the two outer contact jaws 40 to the line terminal clip 32, which is secured to the connector 47 by means such as a'screw 48. Further, as shown in FIGURES 4, 6, and 7, in the first quarter of the wall portion 34, a plurality of conductive straps 49 are secured, the straps 49 extending through a wall 50 of the fuse block and respectively being portions of a plurality of identical load terminals 51, 52, 53, and 54.

The aforementioned spacing of the fuse clips 20 on the fuse holders 12, 12 and of the holes 35, 3:6, and 36a in the wall 34 enables each fuse holder to be received in a recess 14 in either of two positions relative thereto. 'In an on position, the contact blade extensions 26 enter the holes 35 for electrical connection to the legs 38 of the respective contact jaws 40. In a reversed off position, the contact blade extensions 26 enter the holes 36 (one contact blade extension of one fuse holder entering the pocket 36a) and make no electrical connection. The fuse block 1% is provided with on and off indicia adjacent diagonally opposite corners of the recesses 14, as shown in FIGURE 4. When a fuse holder 12 is inserted in a recess, a visual indication of whether it is in off or on position is afforded by the indicia which is left uncovered due to a relieved corner portion of the fuse holder observable at the right thereof in FIGURE 3.

When a fuse holder 12 has a pair of fuses 25 therein and is not in the fuse block it the free end portions of the contact blade extensions 26 of adjacent fuse clips 20 are spaced apart a predetermined distance which is greater than the distance between the legs 38 of the mating contact jaws 40 in the fuse blocks, as shown in exaggerated form in FIGURE 9. When the fuse holder is inserted in the fuse block in an on position, the free end portions of the contact blade extensions are pinched toward each other by engagement with the legs 38 of the contact jaws, as can be seen in a comparison of FIGURES 8 and 9. The pinching of the contact blade extensions 26 toward each other tends to move the outer jaw of each fuse clip 20 toward the inner jaw thereof and establishes better electrical connections between the fuse clips 20 and the fuses 25 than in former constructions. 7 When a fuse holder 12 with a pair of fuses 25 therein is inserted in the on position in the recess 14 adjacent the load terminals 51 and 52, and a load is connected to'the terminals 51 and 52 and the fuse block 10 is energized, an electrical circuit is completed from the line terminal 31 through the connector 44, a first contact jaw 40, a first contact blade extension 26, a first fuse 25, a second contact blade extension 26, a second contact jaw 40, the load terminal 52, the load connected to the terminals 51 and 52, the load terminal 51, a third contact jaw 40, a'third contact blade extension 26, a second fuse 25, afourth contact blade extension 26, a fourth contact jaw 40, the connector 46, and the connector 47 to the line terminal 32. p 7

When a fuse holder 12 with a pair of fuses 25 therein is inserted in the on position in the recess 14 adjacent the load terminals 53 and 54, and a load is connected to theterminals 53 and 54 and the fuse block 10 is energized, an electrical circuit is completed from the line terminal 31thr0ugh the connector 44, the strap 43, a Y

first contact jaw 40, a first contact blade extension 26, a first fuse 25, a second contact blade extension 26, a second contact jaw 40, the'load terminal 53, the load connected to the terminals 53 and 54, the load terminal 54, a third contact jaw 4d, a third contact blade extension '26, a second fuse 25, a fourth contact blade extension 26, a fourth contact jaw 40, and the connector 47 to the line terminal 32.

When a fuse holder 12 with a pair of fuses 25 thereinis inserted in a recess, 14 in the off position, it does not complete an electrical circuit even though a load is connected to the respective load terminals and the fuse block It) is energized, because the contact blade extensions 26 are then in holes 36 and pocket 36a and not in contact with the contact jaws 40.

Various modifications may be made in the structure diclosed without departing from the spirit and scope of the invention.

I claim:

ll. A fusible unit comprising:

(a) a fuse block having an elongated generally rec'- tangular recess therein opening to the front thereof,

(b) an elongated generally rectangular fuse holder selectively received in said recess in either of two relative positions,

(c) said fuse holder having four fuse clips secured to an inner side thereof in a rectangularly spaced arrangement, each fuse clip being adapted to receive an end of a cartridge fuse and being oriented with respect to said fuse holder to accommodate the mounting of two fuses thereon longitudinally thereof,

(d) each fuse clip having a contact blade extension on an outer jaw thereof adjacent a longitudinal edge of'said fuse holder, two of said fuse clips being located a first predetermined distance from one end of said fuse holder and the other two fuse clips being located a second predetermined distance from the other end of said fuse holder, said first and second predetermined distances being substantially different from each other whereby changing said fuse holder from one of said relative positions in said recess to the other of said relative positions in said recess shifts the fuse clips collectively longitudinally of saidrecess, and 7 l (e) four contact jaws mounted in said fuse block and respectively engageable with the contact blade extensions of said fuse clips in only one of the two relative positions in which said fuse holder may be inserted in said recess.

21A fusible unit as claimed in claim ll, wherein said contact jaws are substantially rigid and said contact blade extensions are relatively resilient and wherein the free end portions of each transversely opposite pair of said contact blade extensions are pinched toward each other by a respective transversely opposite pair of said contact jaws in said one relative position in which said fuse holder may be inserted in said recess, whereby said fuse clips more tightly grip fuses therein toirnprove the electrical connections therebetween. V V i 3. A duplex fusible unit comprising:

(a) a fuse block having a pair of elongated generally -rectangular recesses therein opening to the front thereof and also having a wall portion defining the inner ends of both of said recesses, and I l (b) a pair of elongated generally rectangular fuse holder s respectively selectively received in said recesses in either of two relative positions,

(0) each fuse holder having four fuse clips secured to an inner side thereof in a rectangularly spaced arrangement and each fuse clip being adapted to receive an end of a cartridge fuse and having a contact blade extension on an outer jaw thereof adjacent a longitudinal edge of the fuse holder, the spacing of the four fuse clips on each fuse holder longitudinally thereof being such that if the fuse holder is considered to be formed of four substantially equal quarter sections extending consecutively lengthwise 7 thereof, two 'fuse clip s are secured substantially to the first quarter section and two fuse clips are se cured substantially to the third quarter section,

" (d)'said wall portion having sixteen apertures each adapted to receive a contact blade extension of a fuse clip on a fuse holder, each'of the longitudinal edges of said wall portion in each of said recesses having four of said apertures spaced consecutively therealong and only the first and third of said four aper- .tures along each longitudinal edge of the wall portion in each recess having a contact jaw associated therewith for electrical connection to a contact blade extension of a fuse clip on a fuse holder, whereby a fuse holder having a pair of cartridge fuses mounted in the fuse clips thereof-may effect completion of an electrical circuit in only one of said two relative positions in which it may be inserted in a recess.

4. A duplex fusible unit comprising:

(a) a fuse block having a pair of elongated generally rectangular recesses therein opening to the front thereof.

(b) a pair of elongated generally rectangular fuse holders respectively selectively received in said recesses in either of two relative positions,

(0) each fuse holder having four fuse clips secured to an inner side thereof in a rectangularly spaced arrangement, each fuse clip being adapted to receive an end of a cartridge fuse and being oriented with respect to its respective fuse holder to accommodate the mounting of two fuses thereon longitudinally thereof,

(d) each fuse clip having a contact blade extension on an outer jaw thereof adjacent a longitudinal edge of its respective fuse holder, each fuse holder having two of these four fuse clips thereon located a first predetermined distance from one end thereof and the other two fuse clips thereon located a second predetermined distance from the other end thereof, said first and second predetermined distances being substantially different from each other whereby changing a fuse holder from one of its said relative positions in its respective recess to the other of its said relative positions therein shifts the fuse clips collectively longitudinally of the recess, and

(e) eight contact jaws mounted in said fuse block, four of said contact jaws being associated with one of said recesses and four being associated with the other of said recesses, the contact blade extensions of each fuse holder being respectively engageable with the contact jaws associated with its respective recess in only one of the two relative positions in which the fuse holder may be inserted in its recess.

5. A duplex fusible unit comprising: i

(a) a generally rectangular fuse block having a pair of elongated generally rectangular recesses therein opening the front thereof,

(b) a pair of elongated generally rectangular fuse holders respectively selectively received in said recesses in either of two relative positions, each of said fuse holders being adapted to carry a pair of cartridge fuses mountable longitudinally thereof on an inner side,

(c) a row of four load terminals mounted on said fuse block adjacent one end thereof, said row of load terminals extending transversely of said recesses,

(d) a pair of line terminals mounted on said fuse block adjacent the other end thereof,

(e) a first row of four contact jaws mounted on said fuse block, said first row of contact jaws extending transversely of said recesses and parallel to said row of load terminals, said contact jaws of said first row being electrically connected respectively to said load terminals, and

(f) a second row of four contact jaws mounted on said fuse block, said second row of contact jaws extending transversely of said recesses and being parallel to and spaced from said first row of contact jaws, the two inner contact jaws of said second row being electrically connected to one of said line terminals and the two outer contact jaws of said second row being electrically connected to the other of said line terminals, said contact jaws of said first row being adapted to be respectively electrically connected to one end of cartridge fuses mountable on said fuse holders only when said fuse holders are respectively in said recesses in one of said relative positions, and

the electrical connections between said contact jaws of said second row and said line terminals include:

(a) a conductive strap electrically connected to the two inner contact jaws,

(b) a generally U-shaped conductive strap having a bight portion extending between and parallel to said rows of contact jaws and a pair of.relatively short leg portions respectively electrically connected to the two outer contact jaws,

(c) a conductive strap electrically connected to one of the inner contact jaws and to one of said line terminals, and

(d) a conductive strap electrically connected to the outer contact jaw remote from said one of the inner contact jaws and to the other of said line terminals.

7. A duplex fusible unit comprising:

(a) a generally rectangular fuse block having a pair of elongated generally rectangular recesses therein opening to the front thereof,

(b) a pair of elongated generally rectangular fuse holders respectively selectively received in said recesses in either of two relative positions,

(c) each fuse holder having four fuse clips secured to an inner side thereof in a rectangularly spaced arrangement, each fuse clip being adapted to receive an end of a cartridge fuse and being oriented with respect to its respective fuse holder to accommodate the mounting of two fuses thereon longitudinally thereof,

(d) each fuse clip having a contact blade extension on an outer jaw thereof adjacent a longitudinal edge of its respective fuse holder, each fuse holder having two of the four fuse clips thereon located a first predetermined distance from one end thereof and the other two fuse clips thereon located a second predetermined distance from the other end thereof, said first and second predetermined distances being substantially different from each other whereby changing a fuse holder from one of its said relative positions in its respective recess to the other of its said relative positions therein shifts the fuse clips collectively longitudinally of the recess,

(e) a row of four load terminals mounted on said fuse block adjacent one end thereof, said row of load terminals extending transversely of said recesses,

(f) a pair of line terminals mounted on said fuse block adjacent the other end thereof,

(g) a first row of four contact jaws mounted on said fuse block said second row of contact jaws extending transversely of said recesses and parallel to said row of load terminals, said contact jaws of said first row being electrically connected respectively to said load terminals, and

(h) a second row of four contact jaws mounted on said fuse block, said second row of contact jaws extending transversely of said recesses and being parallel to and spaced from said first row of contact jaws, the two inner contact jaws of said second row being electrically connected to one of said line terminals and the two outer contact jaws of said second row being electrically connected to the other of said line terminals, and said contact blade extensions being electrically connected respectively to said contact jaws only when said fuse holders are respectively in said recesses in one of said relative positions.

8. A duplex fusible unit as claimed in claim 7, wherein the electrical connections between said contact jaws of said second row and said line terminals include:

(a) a conductive strap electrically connected to the two inner contact jaws,

(b) a generally U-shaped conductive strap having a bight portion extending between and parallel to said rows of contact jaws and a pair of relatively short leg portions respectively electrically connected to the two outer contact jaws,

(c)' a conductive strap electrically connected to one of the inner contact jaws and to one of said line terminals, and a (d) a conductive strap electrically connected to the outer contact jaw remote from said one of the inner contact jaws and to the other of said line terminals.

0 References Cited by the Examiner UNITED STATES PATENTS" 1,821,987 9/31 Redshaw 317-116 2,423,227 7/47 Cole' 200114 2,899,521 8/59 Salomone 200-114 2,934,679 F 8/60 Johnson et a1. 339198 3,070,679 12/762 Stanback 200-133 BERNARD A. GILI-IEANY, Primary Examiner. 

1. A FUSIBLE UNIT COMPRISING: (A) A FUSE BLOCK HAVING AN ELONGATED GENERALLY RECTANGULAR RECESS THEREIN OPENING TO THE FRONT THEREOF, (B) AN ELONGATED GENERALLY RECTANGULAR FUSE HOLDER SELECTIVELY RECEIVED IN SAID RECESS IN EITHER OF TWO RELATIVE POSITIONS, (C) SAID FUSE HOLDER HAVING FOUR FUSE CLIPS SECURED TO AN INNER SIDE THEREOF IN A RECTANGULARLY SPACED ARRANGEMENT, EACH FUSE CLIP BEING ADAPTED TO RECEIVE AN END OF A CARTRIDGE FUSE AND BEING ORIENTED WITH RESPECT TO SAID FUSE HOLDER TO ACCOMMODATE THE MOUNTING OF TWO FUSES THEREON LONGITUDINALLY THEREOF, (D) EACH SUVE CLIP HAVING A CONTACT BLADE EXTENSION ON AN OUTER JAW THEREOF ADJACENT A LONGITUDINAL EDGE OF SAID FUSE HOLDER, TWO OF SAID FUSE CLIPS BEING LOCATED A FIRST PREDETERMINED DISTANCE FROM ONE END OF SAID FUSE HOLDER AND THE OTHER TWO FUSE CLIPS BEING LOCATED A SECOND PREDETERMINED DISTANCE FROM THE OTHER END OF SAID FUSE HOLDER, SAID FIRST AND SECOND PREDETERMINED DISTANCES BEING SUBSTANTIALLY 